<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <title>Document</title>
</head>
<body>
  <script>
    var oldClass = ['小明', '小强', '小亮', '小东'];
    console.log(oldClass);    // 输出结果：(4) ["小明", "小强", "小亮", "小东"]
    delete oldClass[1];       // 删除数组中第2个元素
    console.log(oldClass);    // 输出结果：(4) ["小明", empty, "小亮", "小东"]
  </script>  
</body>
</html>